Powder coating technology involves applying a coating of a thermoplastic or thermoset polymer powder, for example a polyamide, polyester, polyolefin, urethane, acrylic, fluoropolymer or epoxy system, to a substrate and forming a continuous film by coalescing the polymer particles at temperatures greater than their melting point. In the case of thermoset polymers, the powder is also cured, i.e., polymerized, during the coalescence phase. Generally curing of thermoset powders is initiated thermally or by exposure to radiation, e.g., with ultraviolet (UV) light.
Few techniques are known for applying a surface texture to a powder coated substrate. U.S. Pat. No. 6,238,750, for example, discloses techniques that are said to impart smoothness or texture to a powder coated surface by compressing the surface with a “flexible confining membrane” or “an engraved or etched photolithographic pattern on the pressing surface.” Some commercial processes impart a crude texture to powder coatings by manipulating the coating formulation, for example by using powders having various particle sizes and melting temperatures in the powder coating formulation.